JP2004112903A - Motor circuit and motor control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor circuit and a motor control method for stabilizing an input voltage of an inverter. <P>SOLUTION: Capacitors C1, C2 are connected to the inverters INV1, INV2, respectively, and the capacitors C1, C2 are connected in series to each other. Outputs of the inverters INV1, INV2 are connected to stator coil ends of motors M1, M2, respectively, and a battery B is connected to a neutral point between the motors M1, M2. By controlling switchings of the inverters INV1, INV2, a connection relation between the battery B and the capacitors C1, C2 can arbitrarily be controlled, and then a current of the battery B and voltages of the capacitors C1, C2 are controlled, thus allowing input voltages of the inverters INV1, INV2 to properly be controlled. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a motor circuit for driving two motors by supplying drive currents to two motors from two inverters, and more particularly to a motor circuit in which a DC power source is arranged between neutral points of stator windings of two motors. .
[0002]
[Prior art]
Conventionally, in electric vehicles and hybrid electric vehicles, a system that converts DC power from a mounted battery into a predetermined AC current by an inverter and supplies the AC current to a motor to obtain a motor output corresponding to the amount of accelerator depression has been widely used. Has been adopted.
[0003]
Here, the width of the output torque required for the motor during traveling of the vehicle is very large. In order to obtain a large output from the motor, the lower the power supply voltage is, the larger the current must be flowed. As a result, the loss tends to be large, and the motor must be made large to reduce the loss. On the other hand, if the power supply voltage is high, the loss can be reduced accordingly, but there is a problem that a large number of battery cells need to be connected in series.
[0004]
Further, there is a problem that the battery voltage is liable to fluctuate in accordance with the driving state of the motor, thereby changing the inverter input voltage, making it impossible to perform stable motor drive control.
[0005]
Therefore, there has been proposed a system in which a battery voltage is boosted by a DC-DC converter and the obtained high voltage is used as an input of an inverter.
[0006]
That is, as shown in FIG. 1, the output of the battery B is boosted by the DC-DC converter CONV and supplied to the inverter INV. Then, the inverter INV performs a predetermined switching operation on the boosted DC power, and supplies a predetermined AC current to the motor M. That is, by controlling the switching of the inverter INV based on the motor output torque command, the output current of the inverter INV is controlled so that the motor output torque matches the command.
[0007]
Thus, by providing the DC-DC converter CONV, the voltage of the battery B can be made relatively low, and the motor drive voltage (input voltage of the inverter INV) can be made high. The voltage can be stabilized.
[0008]
Further, the DC-DC converter requires inductance such as a coil, and the circuit becomes relatively large. Therefore, the use of a variable DC voltage type inverter utilizing the inductance of a motor coil in a motor has been studied. That is, as shown in FIG. 2, the positive electrode of the battery B is connected to the neutral point of the motor M, and also connected to the negative bus of the negative inverter INV of the battery B. Further, the output side of the inverter INV is connected to the coil end of each phase of the motor M in the same manner as described above. Then, a capacitor C is connected between the positive and negative buses of the inverter INV.
[0009]
In this variable DC voltage inverter, the DC power from the capacitor C is supplied to the motor M via the inverter INV, but the neutral voltage of the motor is fixed to the voltage Vb of the battery B. Then, considering the total of each phase current of the motor by the inverter INV, an equivalent circuit of the circuit of FIG. 2 is as shown in FIG. If the on-duty of the upper switching element of the inverter INV is equal to the on-duty of the lower switching element, the voltage of the capacitor C should be 2 Vb, which is twice the voltage Vb of the battery B. Therefore, according to this system, the voltage of the battery B can be reduced to half of the input voltage of the inverter INV. Such a system is described in, for example, Japanese Patent Application Laid-Open No. 2001-37247 (Patent Document 1).
[0010]
[Patent Document 1]
JP 2001-37247 A
[0011]
[Problems to be solved by the invention]
Here, the system as shown in FIG. 2 has a problem that a DC-DC converter including a coil is separately required as described above.
[0012]
Further, in the variable DC voltage type inverter using the coil inductance in the motor, the current of the battery B fluctuates greatly, and it is difficult to secure a stable operation. There was a problem of being limited to twice.
[0013]
Furthermore, when a motor and another inverter are separately installed, wiring for connecting the neutral point to the battery is required, so that the power system wiring needs the number of driving phases plus one. there were.
[0014]
The present invention has been made in view of the above problems, and has as its object to provide a motor circuit capable of performing stable operation or simplifying wiring.
[0015]
[Means for Solving the Problems]
The present invention provides two inverters each having a plurality of arms each having a series connection of two switching elements between a positive bus and a negative bus, and outputting the midpoint of the arms, and two inverters. Two motors each having a plurality of stator windings, each connected to an output, each connected in common at a neutral point, and a DC connected between the neutral points of the stator windings of the two motors. A motor having a power supply, two capacitors respectively connected between a positive bus and a negative bus of the two inverters, and a neutral point of a stator winding connected to a positive electrode of the battery. A negative bus of the inverter to be driven is connected to a positive bus of the other inverter.
[0016]
With this configuration, the amount of current in the DC power supply and the voltage of the capacitor can be freely controlled by controlling the inverter. Therefore, the motor can be driven stably by controlling the capacitor voltage without being affected by the voltage fluctuation of the DC power supply. That is, since the inverter has a function of transforming the DC power supply voltage, the drive voltage of the two inverters for driving the two motors can be set to near the optimum value without adding a DC-DC converter. Control and stabilization are possible, and the maximum output can be ensured even when the battery voltage fluctuates. Therefore, it is not necessary to increase the size of the motors, and the specifications of the two motors can be optimized. In particular, since this configuration is a configuration in which both of the two motors are drive-controlled or both are in regenerative control, it is suitable for a two-motor drive or the like in which drive wheels are directly driven. It is possible to optimize and stabilize the driving state of the motor.
[0017]
It is preferable that the withstand voltage of the switching element in each inverter is higher than the voltage of the DC power supply. As a result, a large voltage corresponding to the capacitor voltage is applied to the switching element of each inverter.However, by making the withstand voltage of the switching element of the inverter higher than the DC power supply voltage, measures such as disconnecting the capacitor voltage at the time of stop are taken. Even if not performed, the element will not be destroyed.
[0018]
Preferably, the switching element of each inverter is a MOSFET. As a result, when the DC power supply voltage is approximately 200 V or less, the occurrence of loss in the switching element can be reduced.
[0019]
In addition, it is preferable that the inverter and the motor have an integral structure installed in the same housing. In this way, since the inverter and the motor are integrated, there is little adverse effect due to an increase in the number of wires to an external power supply.
[0020]
In the control method according to the present invention, all the switch elements on the positive bus side of the inverter are turned on, all the switch elements on the negative bus side are turned off, and all the switch elements on the positive bus side of the inverter are turned off. The current flowing through the neutral point of the two motor stator windings and the negative bus of each inverter and the positive bus are switched by switching the low voltage state in which all the switch elements on the negative bus side are turned on by time control between the two inverters. It is characterized in that the voltages of the capacitors respectively connected between the side buses are controlled respectively.
[0021]
The present invention also provides an inverter having a plurality of arms each including a series connection of two switching elements between a positive side bus and a negative side bus, and having an output at a middle point of the arms.
A motor having a plurality of stator windings connected to an output of the inverter and commonly connected at a neutral point, the motor circuit receiving a DC voltage at the neutral point of the motor, And the motor is housed in the same housing.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 4 is a diagram illustrating an example of the motor circuit according to the embodiment. A positive bus and a negative bus of the inverter INV1 are connected to both ends of the capacitor C1. Inverter INV1 has three arms (three phases) formed of two transistors connected in series, and these are connected between a positive bus and a negative bus. The midpoint of each arm is the output end of each phase.
[0024]
Each phase coil end of the motor M1 is connected to each output end of the inverter INV1. The motor M1 is a three-phase PM motor, has a permanent magnet in a rotor, and has a three-phase star connection coil as a stator coil (armature coil).
[0025]
Further, in this embodiment, a capacitor C2, an inverter INV2, and a motor M2 having the same configuration are provided.
[0026]
The positive electrode of the battery B is connected to the neutral point, which is a common connection point of the three-phase coils of the motor M1, and the negative electrode of the battery B is connected to the neutral point of the three-phase coils of the motor M2. Further, the negative bus of the inverter INV1 and the positive bus of the inverter INV2 are connected. That is, the capacitors C1 and C2 are connected in series.
[0027]
In FIG. 4, the switching elements constituting the inverters INV1 and INV2 are MOSFETs, and the breakdown voltage of each MOSFET is larger than the voltage of the battery B, and is approximately twice as large.
[0028]
In such a configuration, the inverters INV1 and INV2 are controlled based on the output torque commands of the motors M1 and M2, and the three-phase motor drive currents to the motors M1 and M2 are controlled. Is controlled in accordance with the output torque command. Further, the regenerative electric power by the motors M1 and M2 is supplied to the capacitors C1 and C2 via the inverters INV1 and INV2, respectively.
[0029]
If the voltages of the capacitors C1 and C2 are Vc1 and Vc2, respectively, and the battery voltage is Vb and the on-duty of the upper switching element and the on-duty of the lower switching element in the inverters INV1 and INV2 are the same, the motors M1 and M2 The neutral point voltages are Vc1 / 2 + Vc2 and Vc2 / 2, respectively. Since the difference between the two becomes the battery voltage Vb, there is a relationship of Vc1 / 2 + Vc2-Vc2 / 2 = Vb, and therefore, Vc1 + Vc2 = 2Vb.
[0030]
Also, in the circuit of FIG. 4, all the upper switching elements of the inverters INV1 and INV2 are turned on and all the lower switching elements are turned off, and conversely, all the upper switching elements of the inverters INV1 and INV2 are turned off and all the lower switching elements are turned off. Can be turned on. FIG. 5A shows an equivalent circuit in this case.
[0031]
By controlling the switching elements of the inverters INV1 and INV2, the current I in the battery B and the voltages Vc1 and VC2 of the capacitors C1 and C2 can be arbitrarily controlled.
[0032]
For example, in FIG. 5A, all the upper switching elements of the inverters INV1 and INV2 are turned on, and all the lower switching elements are turned off (1,1,1) and (1,1,1). Thus, both ends of the battery B are connected to both ends of the capacitor C1 via the motor M1 and the inverter INV1. Therefore, the voltage Vc1 of the capacitor C1 = Vb.
[0033]
In FIG. 5B, all the upper switching elements of the inverters INV1 and INV2 are turned off, and all the lower switching elements are turned on (0, 0, 0) and (0, 0, 0). Thereby, both ends of the battery B are connected to both ends of the capacitor C2 via the motor M2 and the inverter INV2. Therefore, the voltage Vc1 of the capacitor C2 = Vb. Thereby, the fluctuation of the battery current I can be basically set to zero.
[0034]
In the drawing, all of the upper switching elements of the inverters INV1 and INV2 are turned on (all of the lower switching elements are turned off), and all of the upper switching elements are turned off (all of the lower switching elements are turned on). (0, 0, 0).
[0035]
Here, assuming that the respective phase currents of the motors M1 and M2 are Iu1, Iv1, Iw1, Iu2, Iv2 and Iw2, the battery current I for charging and discharging the capacitors C1 and C2 connected in series is the upper three-phase current Iu1. , Iv1, Iw1, that is, I = Iu1 + Iv1 + Iw1, and -I = Iu2 + Iv2 + Iw2 in relation to the lower three-phase currents Iu2, Iv2, Iw2.
[0036]
The current I causes the capacitors C1, C2 connected in series to be charged (during driving) or discharged (during regeneration).
[0037]
The battery current I turns on all the upper switching elements of the inverter INV1 (turns off all the lower switching elements) (1, 1, 1) and sets the upper side of the inverter INV2 so as to have the connection relationship shown in FIG. A state (0, 0, 0) in which all switching elements are turned off (all lower switching elements are turned on) is shown. Thus, when all the switching elements of the inverter INV1 are connected to the high voltage side and all the switching elements of the inverter INV2 are connected to the low voltage side, the battery current I decreases.
[0038]
On the other hand, all the upper switching elements of the inverter INV1 are turned off (all the lower switching elements are turned on) (0, 0, 0), and all the upper switching elements of the inverter INV2 are connected so as to have the connection relationship of FIG. When it is turned on (all the lower switching elements are turned off) (1, 1, 1), the battery current I increases.
[0039]
Therefore, the battery current I can be adjusted to a desired value by appropriately using the connection states shown in FIGS. 6A and 6B. In FIG. 6, the capacitor voltage is Vb.
[0040]
The control time of FIG. 6 is Tj, the voltages between the neutral point of the three-phase coil and the midpoint potential of the series capacitor are V1 and V2, respectively, and the average voltage of V1 and V2 in the control cycle Tj of FIG. , V2j.
[0041]
Next, voltage adjustment between the capacitors C1 and C2 will be described. As shown in FIG. 7A, all the upper switching elements of the inverter INV1 are turned on (all the lower switching elements are turned off) (1, 1, 1), and all the upper switching elements of the inverter INV2 are turned on ( When all the lower switching elements are turned off (1, 1, 1), the upper capacitor C1 is charged (driving) and discharged (regenerated).
[0042]
7B, all upper switching elements of the inverter INV1 are turned off (all lower switching elements are turned on) (0, 0, 0), and all upper switching elements of the inverter INV2 are turned off. When it is turned off (all the lower switching elements are turned on) (0, 0, 0), the lower capacitor C2 is charged (at the time of driving) and discharged (at the time of regeneration).
[0043]
Therefore, the adjustment of the voltages of the capacitors C1 and C2 can be achieved by appropriately using the connection states of FIGS. 7A and 7B. The control time in this case is Tk, V1, and the average of V2 is V1k, V2k.
[0044]
For drive control, for example, vector point control other than the zero vector is performed based on a conventional triangular wave comparison control method. That is, as described above, each phase current of the motors M1 and M2 is controlled based on the output torque command for the motors M1 and M2. The control time at this time is Ti, and the average of V1 and V2 is V1i, V2i.
[0045]
Next, the overall control will be described. First, control is performed on the battery current I. That is, assuming that the battery voltage is Vb, the drive power of the motor (stator coil) M1 driven by the upper inverter INV1 is W1, and the drive power of the lower motor (stator coil) M2 is W2, I × Vb = W1 + W2. Perform control.
[0046]
By this control, the values of Tj, V1j, and V2j are determined. In the case of regeneration, since the values of W1 and W2 are negative, the value of the battery current I is also negative.
[0047]
Next, w1 and W2 are determined and Ti, V1i, and V2i are determined based on a drive current control instruction value (output torque instruction values of the motors M1 and M2).
[0048]
In addition, since the voltages of the capacitors C1 and C2 need to be controlled so that W1 = V1 × I and W2 = V2 × I, V1 = Vb × W1 / (W1 + W2) and V2 = Vb × W2 / (W1 + W2). ), The upper and lower capacitor voltages Vc1 and VC2 are controlled.
[0049]
Specifically, as Tc = Tj + Tk + Ti,
W1 = {(Tj × V1j + Tk × V1k + Ti × V1i) / Tc} × I (1)
W2 = {(Tj × V2j + Tk × V2k + Ti × V2i) / Tc} × I (2)
By adjusting Tk, V1k, and V2k so as to satisfy, the power supplied (regenerated) to the motors M1 and M2 and the drive (regenerated) power are balanced. That is, since W1 = V1.times.I and W2 = V2.times.I, the power flowing into and out of the capacitors C1 and C2 is zero on average, and the capacitor voltage is controlled stably. Note that the capacitor voltages Vc1 and Vc2 are approximately twice V1 and V2.
[0050]
By the control according to the above procedure, it is possible to perform the drive (regeneration) control of the circuit of FIG.
[0051]
Then, the input voltages Vc1 and Vc2 of the inverters INV1 and INV2 are transformed into the optimum voltages of the motors M1 and M2, and the optimum voltages (Vc1 and Vc2) are the same even if the battery voltage (Vb) fluctuates. The voltage is controlled to a constant value. For this reason, the stator coils of the motors M1 and M2 are always controlled at the same optimum voltage regardless of the fluctuation of the battery power supply voltage Vb, so that the motors can always be used with the motor specifications being optimized. . This configuration can be applied even when the optimum driving voltage varies depending on the use conditions.
[0052]
In particular, since the battery B is connected to the neutral point of the two stator coils (motor coils) and the capacitors C1 and C2 are connected to the high and low voltage sides of the inverters INV1 and INV2, the stators of the two motors are connected. When all of the switching elements of one of the inverters INV1 and INV2 are linked and switched to the high voltage side or the low voltage side, the coil simply acts as a coil. Therefore, when viewed from the capacitors connected to the high voltage side and the low voltage side of the two inverters INV1 and INV2, they operate as two DC-DC converters. Therefore, it is possible to optimally drive the voltages of the two capacitors C1 and C2, that is, the input voltages of the inverters INV1 and INV2, according to the driving conditions.
[0053]
In addition, since the time required for the operation of the DC-DC converter is short, the normal driving can be performed in substantially the same manner as the normal driving by combining and switching the switches of the respective inverters.
[0054]
The switching elements of the inverters INV1 and INV2 are configured by MOSFETs. As a result, when the battery B voltage is approximately 200 V or less, the occurrence of loss in the switching element can be reduced.
[0055]
Next, in the case of a single phase, the configuration is as shown in FIG. In this configuration, each of the inverters INV1 and INV2 has only two arms, and the motors M1 and M2 have only two-phase stator coils.
[0056]
Even in such a configuration, all of the upper switching elements of the inverters INV1 and INV2 can be turned on (or off) and all of the lower switching elements can be turned on (or off) in the same manner, and basically the same control can be performed. .
[0057]
Further, FIG. 9 shows a configuration in which the motors M3 and M4 are connected to the capacitors C1 and C2 via other inverters INV3 and INV4. According to such a configuration, the other motors M3 and M4 can be driven using the capacitors C1 and C2 as power sources. In this case, it is necessary to add the outputs W3 and W4 of the motors M3 and M4 to the output to perform overall control.
[0058]
The stator coil (armature coil) in a single motor is composed of a plurality of pole pairs in the case of a motor of several tens of kW class. For this reason, it is possible to treat the motor as the same as two motors by driving the motor in two parts.
[0059]
In this case, a structure in which the inverter is installed in the motor housing is advantageous in order to reduce the number of wires between the motor and the inverter.
[0060]
FIG. 10 shows an example in which a motor and a motor circuit such as an inverter are accommodated in one housing.
[0061]
A pair of bearings 32 is provided at the center of the front and rear surfaces (left and right sides in the figure) of the housing 30, and a shaft 34 that penetrates the housing 30 is rotatably supported by the bearings 32. A rotor 36 is fixed to an intermediate portion of the shaft 34 in the housing 30. The rotor 36 is provided with a predetermined number of permanent magnets corresponding to the number of poles.
[0062]
A stator 38 made of a silicon steel plate is arranged so as to surround the periphery of the rotor 36. A plurality of stator coils (armature coils) 40 are fixed to the stator 38. Thus, the PM motor is configured.
[0063]
An inverter 42 is housed in the housing 30. In the figure, an end is fixed to a peripheral portion of the stator 38, and a mounting plate 44 which is formed so as to bulge so as to cover the rear side of the stator 38 and the rotor 36 is provided. I have. The inverter 42 includes a switch element mounting board on which a plurality of switching elements 42a made of MOSFETs are mounted. Further, a water cooling mechanism 46 for cooling the switching element on the front side (left side in the figure) of the inverter 42 is arranged.
[0064]
Although only two are shown in the figure, the inverter 42 and the stator coil 40 are connected by three connection lines 48. Also, two connection terminals 50 with the battery are provided, the connection terminal 50 with the battery positive electrode is connected to the neutral point of the stator coil 40, and the negative electrode is connected to the negative electrode bus of the inverter circuit 42.
[0065]
Furthermore, one capacitor C is built in, and is connected to the inverter 42 by a connection line 52. That is, both ends of the capacitor C are connected to the positive bus and the negative bus of the inverter circuit 42. As described above, by incorporating the capacitor C, only two terminals for connection to the outside are required for connection to the battery.
[0066]
Thus, a circuit as shown in FIG. 2 is configured. When all of the stator coils (armature coils) 40 are switched in phase, the circuit of FIG. 2 can be treated as one coil mainly due to the parasitic inductance component, so that the circuit of FIG. It is described with one arm.
[0067]
If the circuit as shown in FIG. 4 is configured, two terminals of a neutral point and terminals respectively connected to the negative bus of the inverter circuit 40 are provided from one of the motors. It is sufficient to take out the neutral point and the positive bus of the inverter circuit 40 as terminals. If a capacitor is provided externally, both motors may be provided with terminals connected to the positive and negative buses of the inverter circuit 40, and three terminals may be provided for each.
[0068]
As described above, by integrating the motor with the inverter while having the DC voltage variable function, it is possible to configure a compact motor drive system with a small number of wires.
[0069]
As described above, since the number of wirings of the power system is only two in connection with the battery by being integrated, the overall cost can be reduced. In particular, it has a variable voltage (step-up) function with respect to fluctuations in the battery power supply voltage, and it is possible to always optimize and stabilize the drive voltage of the inverter, so that the size of the motor can be minimized. In addition, there is no need to externally attach a DC-DC converter, and the capacity of the inverter element needs to be slightly increased, so that the overall configuration can be reduced in size. Also, the number of wires for the power system is only two even in the case of a polyphase drive motor. In particular, it is preferable that a capacitor is also incorporated in the housing.
[0070]
In the above description, the upper switching element and the lower switching element are all turned on or off to adjust the battery current or the like. However, it is not always necessary to perform all on and all off control.
[0071]
That is, by changing the ratio between the on-duty of the upper switching element and the on-duty of the lower switching element in the inverters INV1 and INV2, it is possible to perform control equivalent to turning on and off all the upper and lower switching elements. it can.
[0072]
For example, if the on-duty of the upper switching element is set to 1/3 (the on-duty of the lower switching element is set to 2/3), the neutral point potential becomes 1/3 of the input voltage of the inverter.
[0073]
Therefore, assuming that the on-duty of the upper switching element of the inverter INV2 is １ ／ and the on-duty of the upper switching element of the inverter INV1 is １ ／, the neutral point potential of the motor M2 is Vc2 / 3 and the neutral point of the motor M1 is neutral. The point potential is (Vc2) / 3 + Vb. The neutral point voltage of the motor M1 is (Vc1) / 2 + (Vc2). Therefore, (Vc2) / 3 + Vb = (Vc1) / 2 + Vc2 → Vb = (Vc1) / 2 + (Vc2) × 2/3.
[0074]
Even with such control, control similar to the above-described case can be performed.
[0075]
【The invention's effect】
As described above, according to the present invention, the amount of current in the DC power supply and the voltage of the capacitor can be freely controlled by controlling the inverter. Therefore, the motor can be driven stably by controlling the capacitor voltage without being affected by the voltage fluctuation of the DC power supply. That is, since the inverter has a function of transforming the DC power supply voltage, the drive voltage of the two inverters for driving the two motors can be adjusted to near the optimum value without adding a DC-DC converter. Control and stabilization, and the maximum output can be ensured even when the battery voltage fluctuates, so that there is no need to increase the size of the motors and the specifications of the two motors can be optimized. In particular, since this configuration is a configuration in which both of the two motors are drive-controlled or both are in regenerative control, it is suitable for a two-motor drive or the like in which drive wheels are directly driven. It is possible to optimize and stabilize the driving state of the motor.
[0076]
Further, since the withstand voltage of the switching element in each inverter is higher than the voltage of the DC power supply, a large voltage corresponding to the capacitor voltage is applied to the switching element of each inverter. By making it large, the element will not be destroyed without taking measures such as disconnecting the capacitor voltage when stopping.
[0077]
Further, since the switching element of each inverter is a MOSFET, when the DC power supply voltage is approximately 200 V or less, the generation of loss in the switching element can be reduced.
[0078]
In addition, since the inverter and the motor have an integrated configuration installed in the same housing, adverse effects due to an increase in the number of external wirings are small.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a conventional example.
FIG. 2 is a diagram showing a configuration of another conventional example.
FIG. 3 is a diagram showing an equivalent circuit of another conventional example.
FIG. 4 is a diagram illustrating a configuration of an example of an embodiment;
FIG. 5 is a diagram illustrating an example of connection of inverters.
FIG. 6 is a diagram showing control of a battery current.
FIG. 7 is a diagram showing voltage control of a capacitor.
FIG. 8 is a diagram illustrating a configuration of single-phase driving.
FIG. 9 is a diagram showing a configuration of an application example.
FIG. 10 is a diagram showing a configuration when housed in a housing.
[Explanation of symbols]
B Battery, C1, C2 capacitors, INV1, INV2 inverters, M1, M2 motors.

Claims (6)

Two inverters each having a plurality of arms each having a series connection of two switching elements between a positive bus and a negative bus, and having a middle point as an output;
Two motors respectively connected to the outputs of the two inverters and each having a plurality of stator windings commonly connected at a neutral point;
A DC power supply connected between the neutral points of the stator windings of the two motors,
Two capacitors respectively connected between a positive bus and a negative bus of the two inverters;
Has,
A motor circuit in which a negative bus of an inverter for driving a motor in which a neutral point of a stator winding is connected to a positive side of the battery and a positive bus of the other inverter are connected. The circuit according to claim 1,
A motor circuit in which a withstand voltage of a switching element in each inverter is higher than a voltage of the DC power supply. The circuit according to claim 1 or 2,
A motor circuit in which the switching element of each inverter is a MOSFET. The circuit according to any one of claims 1 to 3,
A motor circuit having an integral configuration in which the inverter and the motor are installed in the same housing. 5. The circuit according to claim 1, wherein all of the switch elements on the positive bus side of the inverter are turned on, all of the switch elements on the negative bus side are turned off, and the positive bus side of the inverter. The current flowing through the neutral point of the two motor stator windings and the respective inverters are switched by time control between the two inverters in a low voltage state in which all of the switch elements are turned off and all of the switch elements on the negative bus side are turned on. A motor control method for controlling the voltages of the capacitors respectively connected between the negative bus and the positive bus. An inverter having a plurality of arms each having a series connection of two switching elements between a positive bus and a negative bus, and having an output at a midpoint of the arm;
A motor having a plurality of stator windings connected to an output of the inverter and commonly connected at a neutral point, the motor circuit receiving a DC voltage at the neutral point of the motor,
A motor circuit in which the inverter and the motor are housed in the same housing.

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